Double Jupiter-Sized 'Super-Puff' Planets Dazzle with Cotton-Candy Densities

Astronomers have identified two Jupiter-sized exoplanets in the TOI-791 system—TOI-791b and TOI-791c—that are extraordinarily low-density, with densities of about 0.038 and 0.047 g/cm³, among the lowest for giant planets and even lower than cotton candy. Found by citizen scientists via the Planet Hunters TESS project, these planets orbit a dwarf star roughly 1,110 light-years away in a 5:3 resonance. Masses and densities were derived from global observations, including an Antarctic telescope, enabling the team to measure their diffuse nature. Further studies, including space-based observations with the James Webb Space Telescope, are planned to explore their atmospheres and formation history.